1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * vpd_decode.c
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Google VPD decoding routines.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Copyright 2017 Google Inc.
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #include "vpd_decode.h"
11*4882a593Smuzhiyun
vpd_decode_len(const u32 max_len,const u8 * in,u32 * length,u32 * decoded_len)12*4882a593Smuzhiyun static int vpd_decode_len(const u32 max_len, const u8 *in,
13*4882a593Smuzhiyun u32 *length, u32 *decoded_len)
14*4882a593Smuzhiyun {
15*4882a593Smuzhiyun u8 more;
16*4882a593Smuzhiyun int i = 0;
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun if (!length || !decoded_len)
19*4882a593Smuzhiyun return VPD_FAIL;
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun *length = 0;
22*4882a593Smuzhiyun do {
23*4882a593Smuzhiyun if (i >= max_len)
24*4882a593Smuzhiyun return VPD_FAIL;
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun more = in[i] & 0x80;
27*4882a593Smuzhiyun *length <<= 7;
28*4882a593Smuzhiyun *length |= in[i] & 0x7f;
29*4882a593Smuzhiyun ++i;
30*4882a593Smuzhiyun } while (more);
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun *decoded_len = i;
33*4882a593Smuzhiyun return VPD_OK;
34*4882a593Smuzhiyun }
35*4882a593Smuzhiyun
vpd_decode_entry(const u32 max_len,const u8 * input_buf,u32 * _consumed,const u8 ** entry,u32 * entry_len)36*4882a593Smuzhiyun static int vpd_decode_entry(const u32 max_len, const u8 *input_buf,
37*4882a593Smuzhiyun u32 *_consumed, const u8 **entry, u32 *entry_len)
38*4882a593Smuzhiyun {
39*4882a593Smuzhiyun u32 decoded_len;
40*4882a593Smuzhiyun u32 consumed = *_consumed;
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun if (vpd_decode_len(max_len - consumed, &input_buf[consumed],
43*4882a593Smuzhiyun entry_len, &decoded_len) != VPD_OK)
44*4882a593Smuzhiyun return VPD_FAIL;
45*4882a593Smuzhiyun if (max_len - consumed < decoded_len)
46*4882a593Smuzhiyun return VPD_FAIL;
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun consumed += decoded_len;
49*4882a593Smuzhiyun *entry = input_buf + consumed;
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun /* entry_len is untrusted data and must be checked again. */
52*4882a593Smuzhiyun if (max_len - consumed < *entry_len)
53*4882a593Smuzhiyun return VPD_FAIL;
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun consumed += *entry_len;
56*4882a593Smuzhiyun *_consumed = consumed;
57*4882a593Smuzhiyun return VPD_OK;
58*4882a593Smuzhiyun }
59*4882a593Smuzhiyun
vpd_decode_string(const u32 max_len,const u8 * input_buf,u32 * consumed,vpd_decode_callback callback,void * callback_arg)60*4882a593Smuzhiyun int vpd_decode_string(const u32 max_len, const u8 *input_buf, u32 *consumed,
61*4882a593Smuzhiyun vpd_decode_callback callback, void *callback_arg)
62*4882a593Smuzhiyun {
63*4882a593Smuzhiyun int type;
64*4882a593Smuzhiyun u32 key_len;
65*4882a593Smuzhiyun u32 value_len;
66*4882a593Smuzhiyun const u8 *key;
67*4882a593Smuzhiyun const u8 *value;
68*4882a593Smuzhiyun
69*4882a593Smuzhiyun /* type */
70*4882a593Smuzhiyun if (*consumed >= max_len)
71*4882a593Smuzhiyun return VPD_FAIL;
72*4882a593Smuzhiyun
73*4882a593Smuzhiyun type = input_buf[*consumed];
74*4882a593Smuzhiyun
75*4882a593Smuzhiyun switch (type) {
76*4882a593Smuzhiyun case VPD_TYPE_INFO:
77*4882a593Smuzhiyun case VPD_TYPE_STRING:
78*4882a593Smuzhiyun (*consumed)++;
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun if (vpd_decode_entry(max_len, input_buf, consumed, &key,
81*4882a593Smuzhiyun &key_len) != VPD_OK)
82*4882a593Smuzhiyun return VPD_FAIL;
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun if (vpd_decode_entry(max_len, input_buf, consumed, &value,
85*4882a593Smuzhiyun &value_len) != VPD_OK)
86*4882a593Smuzhiyun return VPD_FAIL;
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun if (type == VPD_TYPE_STRING)
89*4882a593Smuzhiyun return callback(key, key_len, value, value_len,
90*4882a593Smuzhiyun callback_arg);
91*4882a593Smuzhiyun break;
92*4882a593Smuzhiyun
93*4882a593Smuzhiyun default:
94*4882a593Smuzhiyun return VPD_FAIL;
95*4882a593Smuzhiyun }
96*4882a593Smuzhiyun
97*4882a593Smuzhiyun return VPD_OK;
98*4882a593Smuzhiyun }
99